SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '78c01551a3330f950b7ea08bc0fbb78edd50f706f0d315d2b67ee9c05751967d' 
  AND token = 'rM9K4kSr3uvc3ollBZ+VHrMebetknQpYCxZZFw4SZ2w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}